mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 20:13:05 +02:00
99 lines
2.7 KiB
C++
99 lines
2.7 KiB
C++
// OpenVPN -- An application to securely tunnel IP networks
|
|
// over a single port, with support for SSL/TLS-based
|
|
// session authentication and key exchange,
|
|
// packet encryption, packet authentication, and
|
|
// packet compression.
|
|
//
|
|
// Copyright (C) 2012-2015 OpenVPN Technologies, Inc.
|
|
//
|
|
// This program is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Affero General Public License Version 3
|
|
// as published by the Free Software Foundation.
|
|
//
|
|
// This program is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Affero General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Affero General Public License
|
|
// along with this program in the COPYING file.
|
|
// If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
#ifndef OPENVPN_COMMON_HASH_H
|
|
#define OPENVPN_COMMON_HASH_H
|
|
|
|
#include <cstdint> // for std::uint32_t, uint64_t
|
|
#include <functional>
|
|
|
|
#include <openvpn/common/size.hpp>
|
|
|
|
#ifdef _MSC_VER
|
|
#define HAVE_HASH_COMBINE 0 // no hash combine on MSVC due to lack of SFINAE
|
|
#else
|
|
#define HAVE_HASH_COMBINE 1
|
|
#endif
|
|
|
|
namespace openvpn {
|
|
namespace Hash {
|
|
|
|
#if HAVE_HASH_COMBINE
|
|
|
|
template <class T>
|
|
inline auto combine(std::size_t& seed, const T& v) -> decltype(std::hash<T>(), void())
|
|
{
|
|
std::hash<T> hasher;
|
|
seed ^= hasher(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
|
|
}
|
|
|
|
template <class T>
|
|
inline auto combine(std::size_t& seed, const T& v) -> decltype(hash_value(v), void())
|
|
{
|
|
seed ^= hash_value(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
|
|
}
|
|
|
|
// A hasher that combines a data hash with a stateful seed.
|
|
template <typename T>
|
|
class InitialSeed
|
|
{
|
|
public:
|
|
InitialSeed(std::size_t seed) : seed_(seed) {}
|
|
|
|
std::size_t operator()(const T& obj) const
|
|
{
|
|
std::size_t seed = seed_;
|
|
combine(seed, obj);
|
|
return seed;
|
|
}
|
|
|
|
private:
|
|
std::size_t seed_;
|
|
};
|
|
|
|
inline void combine_data(std::size_t& seed, const void *data, std::size_t size)
|
|
{
|
|
while (size >= sizeof(std::uint32_t))
|
|
{
|
|
combine(seed, static_cast<const std::uint32_t*>(data)[0]);
|
|
data = static_cast<const std::uint8_t*>(data) + sizeof(std::uint32_t);
|
|
size -= sizeof(std::uint32_t);
|
|
}
|
|
switch (size)
|
|
{
|
|
case 1:
|
|
combine(seed, static_cast<const std::uint8_t*>(data)[0]);
|
|
break;
|
|
case 2:
|
|
combine(seed, static_cast<const std::uint16_t*>(data)[0]);
|
|
break;
|
|
case 3:
|
|
combine(seed, static_cast<const std::uint16_t*>(data)[0]);
|
|
combine(seed, static_cast<const std::uint8_t*>(data)[2]);
|
|
break;
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#endif
|